Evaluation of a proposed expert system development methodology: Two case studies

Two expert system development projects were studied to evaluate a proposed Expert Systems Development Methodology (ESDM). The ESDM was developed for use at Goddard Space Flight Center (GSFC) to provide guidance to managers and technical personnel and serve as a standard in the development of expert systems. It was agreed that the proposed ESDM must be evaluated before it could be adopted; therefore a study was planned for its evaluation. This detailed study is now underway. Before the study began, however, two ongoing projects were selected for a retrospective evaluation. They were the Ranging Equipment Diagnostic Expert System (BCAUS). Both projects were approximately 1 year into development. Interviews of project personnel were conducted, and the resulting data was used to prepare the retrospective evaluation. Decision models of the two projects were constructed and used to evaluate the completeness and accuracy of key provisions of ESDM. A major conclusion reached from these case studies is that suitability and risk analysis should be required for all AI projects, large and small. Further, the objectives of each stage of development during a project should be selected to reduce the next largest remaining area of risk or uncertainty on the project.     

New modelling strategy for representing asymmetric traffic loads on LANs

A new technique for modelling asymmetric traffic load distributions on local area networks (LANs) is presented. The traffic model which is analytical and easy to implement into discrete event computer simulations also has the benefit of providing expressions for the higher mathematical moments of the traffic load distribution.<>     

突发式连续波发射机工作方式的设计

本文较详细地讨论了突发式连续波发射机工作的设计思想,设计方法,采用的技术措施。     

用于锁模光纤激光陀螺的相敏检测

通过采用锁相放大器,演示了一种性能明显提高的锁模光纤激光陀螺.结果表明锁相放大器的输出与转动速率之间具有理想的线性关系,并对两脉冲(在时间间隔测量过程中引起相位误差)之间的光强差不敏感.与以往报道的时间间隔测量相比,演示了长期稳定性提高了二个数量级.     

我国卫星测控系统发展概况及几点建议

本文介绍了我国国内C频段、国际C频段两个卫星测控网站,三代典型微波统一测控系统的特点,提出了对新型航天测控设备研制的建议。     

Task performance of black and white children across levels of presentation variability

This study is an examination of the task performance patterns of Black and White, working and middle-class American children across a nonvaried and a varied presentation format condition: the relation of such patterns to activity levels in the home and to standardized achievement was also examined. Performance was better under the varied than the nonvaried format condition. This pattern held for all ethnic group/class combinations with the exception of Black middle-class children, for whom performance under the two conditions was virtually identical. Moreover, Black children, especially Black working-class children, reported greater home activity levels than did their White counterparts. Neither home activity level nor achievement was functionally related to patterns of performance.     

全球光通信市场最新动向

全球光通信市场经过两年多的萧条，现已基本“触底”，出现反弹和恢复增长已是大势所趋。特别是随着带宽需求的增长，2004年以后多数光通信市场将进入新的增长期，为供应商和运营商提供新的赢利机会。     

MODELING OF INTEGRATED MANUFACTURING SYSTEMS USING AN OBJECT-ORIENTED APPROACH

Traditional approaches to the modeling of complex manufacturing systems are expensive, time consuming, and of limited value. Recent developments in several areas (i.e., knowledge engineering, software engineering, modeling formalisms, engineering workstations, and database systems) are now to the point that a meaningful convergence can be crafted to yield a modeling environment far superior to any we have known in the past. Fundamental to this new approach to modeling are the recent developments in object-oriented programming and related technologies. A research team at Oklahoma State University has been exploring alternative approaches to the modeling and simulation of complex manufacturing systems since 1985. This paper argues for a fundamental paradigm shift in the development and utilization of models within a CEM framework.